The Sumatran ground cuckoo (Carpococcyx viridis) is a large, terrestrial species of cuckoo. It was introduced to Western science in 1879 and was formerly considered conspecific with the Bornean ground cuckoo but was given status as a unique species in 2000. This elusive species was initially known from just eight specimens and evaded notice from 1916 until 1997, when it was rediscovered and photographed by Andjar Rafiastanto. The Sumatran ground cuckoo's diet is thought to consist of invertebrates, small mammals, and reptiles. Characteristics The Sumatran ground cuckoo is a large, terrestrial bird with a long, full tail. Adult birds reach an average length of 55 cm. Its bill and sturdy legs are both green and it has a black crown, shading to green on hind crown. Its mantle, upper back, neck sides, lower throat, upper breast, wing-coverts and secondaries are dull green and its lower back is brown with broad greenish-brown bars. The wings and tail are glossy and greenish-black. The rest of its underparts are cinnamon-buff, more rufous on flanks and it displays striking green, lilac and blue bare skin around the eyes. Its repertoire of vocalizations is little-known but one recently recorded call consisted of repeated low whistles, falling then rising in tone and issued in a rising series (we-ow-we, we-ow-we, we-ow-we, we-ow-we; each phrase slightly higher than last). Distribution and habitat The Sumatran ground cuckoo is endemic to Indonesia and is found exclusively on the island of Sumatra. Notes on early specimen labels suggest its favoured habitat is foothills and primary montane rainforest, and this is reinforced by the locations of recent sightings. It has been found between elevations of 300 and 1400 metres. Because it is so rare today, a considerable body of information on the Sumatran ground cuckoo comes only from the records of Tommaso Salvadori, the Italian ornithologist and zoologist who discovered it; there does not seem to have been much effort to learn more about the bird from locals. It is estimated by the IUCN Red List of Threatened Species that the total population of Sumatran ground cuckoos ranges from 50 to 249 mature individuals, and its population is thought to be decreasing. It is considered one of the 100 most endangered bird species in the world. Like its close relative the Bornean ground cuckoo it is considered unobtrusive, which may further account for the lack of sightings. Most modern-day sightings have taken